1. Field
The invention is in the field of acoustic mufflers and exhaust systems for automobiles, and more specifically mufflers for reducing acoustic noise produced by race cars while minimizing the reduction of engine performance due to increased exhaust gas backpressure, and thin exhaust pipes for increased ground clearance on race cars used on oval tracks such as stock cars.
2. State of the Art
Race cars used in automobile racing are typically constructed such that only a minimal amount of clearance is maintained between the underside of the car and the surface of the roadway or track. This is done to lower the center of gravity of the vehicle so as to improve vehicle handling and resistance to rolling over, and to minimize the drag on the car due to air passing thereunder. Likewise, such race cars typically have very stiff suspension systems which do not allow the vehicle to travel as great a distance up and down nor side-to-side as a standard production car allowing the use of less ground clearance. One of the problems encountered in lowering the race car closer to the race track is providing sufficient clearance for the vehicle exhaust system which is one of the lowest hanging components of a typical car, including race cars.
The problem is particularly acute on cars which race on oval race tracks such as stock cars. The exhaust pipes of such stock cars typically exit toward one or both sides of the car so as to minimize the length of the exhaust pipes and the resulting exhaust gas back pressure which back pressure lowers engine power output and overall engine performance. As such, the minimum ground clearance of the exhaust system typically occurs where the exhaust pipes cross under the longitudinally-extending main frame members of the chassis at the sides of the vehicle. Stock cars typically race on oval tracks in a counter-clockwise rotational direction with centrifugal force causing the body and chassis of the car to lean toward the outside of the turn or toward the right side of the car. Therefore, the ground clearance on the right side of the car is less during cornering and the greatest ground clearance results on the left side of the car during such cornering. Also, banked tracks can induce high downward loads to the suspension system of stock cars requiring additional ground clearance. In an effort to increase the ground clearance of the exhaust system on stock cars, thin profile boom tube exhaust pipes were developed which extend at a rearward, laterally outwardly-directed angle from the secondary exhaust pipes under the main frame members of the chassis. The outlet end of such boom tube exhaust pipe is typically manufactured in a squared-off or right angle end configuration and trimmed at installation to match exit angle and the side of the particular vehicle.
The construction of prior art boom tube exhaust pipes typically takes several forms. A first type of prior art boom tube includes a thin profile, generally flattened sheet metal body having a pair of spaced, parallel flat upper and lower sheet metal pieces and a pair of elongate, U-shaped cross-section sheet metal side pieces welded to respective side edges of the upper and lower sheet metal pieces so as to form a generally flattened tubular body. The upper and lower sheet metal pieces can be tapered so as to form a laterally tapered body which allows the exhaust gasses to expand while traveling therethrough. The upper and lower sheet metal pieces are typically interconnected by a plurality of short rods welded into staggered mating holes in such upper and lower sheet metal pieces. The rods are an attempt to minimize vibration of the broad upper and lower half shells which vibration can cause increased exhaust gas back pressure, resonance and increased noise, and metal fatigue. The boom tube exhaust pipe further includes a single funnel shaped inlet or a pair thereof which is welded to one end of the generally flattened tubular body to connect with the secondary exhaust pipe or pipes of the vehicle. Such inlets typically comprise a longitudinally split thin walled metal tube, the respective halves of which are partially flattened, more so at one end than the other end, and each longitudinally welded at the edges thereof to a pair of upper and lower tapered flat plates, the narrower edge thereof being adjacent the less-flattened ends of the respective half tubes so as to form a generally funnel shaped inlet with a somewhat flattened circular inlet end and a generally flattened profile outlet end. Alternatively, such inlets can comprise a thin walled metal tube into the respective ends of which are forced appropriately shaped arbors or forms which stretch and form the tube into a somewhat flattened circular shaped inlet end and a generally flattened profile outlet end. Such boom tube exhaust pipe is expensive to manufacture due to the multitude of rods and welding involved and is still prone to metal fatigue due to the increased stresses in the half shells at the respective holes therethrough and due to the increased brittleness of the metal of the half shells and rods due to the heat applied during welding thereof.
A second type of prior art boom tube exhaust pipe comprises a large diameter, thin walled steel tube which is generally flattened so as to form a thin profile, generally flattened tubular body. The upper and lower portions of the tubular body can be interconnected by a plurality of rods as explained for the first version prior art boom tube exhaust pipe. A single funnel shaped inlet or a pair thereof of similar construction as that of the first version prior art boom tube is welded to one end of the flattened tubular body to connect with the secondary exhaust pipe or pipes of the vehicle. The tubular body of such boom tube exhaust pipe does not taper outwardly from the inlet end to the outlet end due to fabrication from a tube such that exhaust gasses cannot expand while moving therethrough, causing increased exhaust gas back pressure and suffers from the same disadvantages as the first version prior art boom tube exhaust pipe.
A third type of prior art boom tube takes the form of a rectangular extruded steel tube to which a pair of elongate U-shaped cross-section sheet metal side pieces are welded to the sides thereof to form a thin profile, generally flattened tubular body having three elongate passageways therein. A plurality of exhaust crossover holes are typically drilled or milled through the walls of the tube to allow crossover flow of exhaust gasses between the elongate passageways. A single funnel shaped inlet or a pair thereof of similar construction as that of the first version prior art boom tube is welded to one end of the flattened tubular body to connect the secondary exhaust pipe or pipes of the vehicle to direct the exhaust gasses into the ends of the respective tubes. A plurality of such rectangular tubes (or square tubes) can be welded together side-by-side in place of the single rectangular tube with the sheet metal side pieces welded to the two outermost tubes to form a thin profile, generally flattened tubular body of greater width than using a single rectangular tube. A plurality of exhaust crossover holes are typically drilled or milled through the walls of the tubes to allow crossover flow of exhaust gasses between the elongate passageways. A single funnel shaped inlet or a pair thereof is welded to one end of the flattened tubular body to connect the secondary exhaust pipe or pipes of the vehicle to direct the exhaust gasses into the ends of the respective tubes. While such boom tube exhaust pipe is more fatigue resistant than the sheet metal, the weight thereof is greater, the exhaust gas crossover tubes must typically be drilled or milled rather than less expensive punching thereof, and the body is not tapered such that exhaust gasses cannot expand while traveling therethrough, resulting in increased exhaust gas back pressure.
Such prior art boom tube exhaust pipes can be constructed such that the inlet is at or above a lower plane of the body thereof so as to maximize ground clearance. Likewise, exhaust systems comprising a pair of headers each including a plurality of primary exhaust pipes which connect at one end thereof to the cylinder block of an internal combustion engine at respective exhaust outlet ports thereof and at opposite ends thereof which converge into a single merge collector, a pair of secondary exhaust pipes which connect to the outlet of the respective merge collectors, and one or two boom tube exhaust pipes are used in auto racing. Such exhaust systems can be made and mounted to a race car such that the entire exhaust system, including the inlets of the boom tube exhaust pipes, are at or above the lower plane of the bodies of the boom tube exhaust pipes to maximize ground clearance of the exhaust system.
Such prior art boom tube exhaust pipes are not specifically designed to act as acoustic mufflers and are therefore not effective at reducing acoustic noise. This may be because any baffles or other such device used in prior art mufflers other than that disclosed in my U.S. Pat. No. 5,824,972 tend to decrease engine horsepower and torque to unacceptably low levels due to the increase in engine exhaust gas backpressure caused by such devices.
There are basically two types of prior art acoustic mufflers which have been used, but applicant is not aware of any such acoustic mufflers being combined with a boom tube exhaust pipe. The two types are friction mufflers which mix the gas flow to break up the sound waves, and absorption mufflers which absorb the sound waves in an acoustic damping material.
The friction type muffler is used most frequently, particularly on automobiles. This type of muffler has a casing with an inlet and outlet which can be positioned in a variety of locations, and a series of baffle plates therebetween to direct the gas flow in a circuitous route from inlet to outlet to cause mixing of the gas flow. Offset perforated inlet and outlet pipes may each extend the length of the casing to provide the circuitous route. Friction type mufflers are generally quite effective at reducing noise levels, but because of the circuitous route followed by the exhaust gases passing through the muffler, offer substantial resistance to gas flow. Therefore, significant pressure is required to force the gases through the muffler. This pressure, referred to as back pressure, reduces the efficiency and power output of the engine being muffled.
The absorption type muffler has a casing with a pipe extending completely therethrough. A portion of the pipe inside the casing is perforated and the space between the pipe and casing is filled with sound absorbing fiberglass, ceramic fibers, or metallic wool mesh to absorb sound waves. By allowing the exhaust gases to pass directly through the muffler, the pressure required to push the gas through the muffler is significantly reduced. Therefore, the back pressure is much less than with friction type mufflers and more power is obtained from the engine. However, the sound attenuation is much less than with friction mufflers, and such mufflers are unacceptable in most uses.
Muffler acoustic efficiency is measured in decibels of noise attenuation (dba) versus gas flow in cubic feet per minute (CFM). When a pressure difference of 5 inches of water is imposed between the inlet and outlet, and using a common 2xc2xd inch diameter muffler inlet and outlet, friction type mufflers have about 13-20 dba attenuation and 70-100 CFM flow. Absorption type straight through mufflers under those conditions have an attenuation of about 2-7 dba and 200 CFM flow.
There is a need in many applications for a muffler which has greater acoustic attenuation than the absorption type muffler with higher flow rates and less back pressure than the friction type mufflers.
In my U.S. Pat. No. 5,824,972 is disclosed an acoustic muffler which provides superior acoustic attenuation with minimal increase in exhaust gas backpressure. The acoustic muffler comprises a conventional sheet metal casing which has an inlet and an outlet at opposite ends thereof. A flow of gas containing acoustic noise flows from inlet to outlet. A plurality of spiral acoustic traps, each of which extend from bottom to top of the casing, have a central axis positioned perpendicular to the gas flow. An opening in each spiral acoustic trap extends into the gas flow to divert some gas into the trap, wherein the gas flows in a circular path so as to degrade and randomize the sound waves into heat, by utilizing a circular mixing process with increased gas retention time. Gas is drawn out of the acoustic trap through a series of vent holes in the acoustic trap on the back side of the acoustic trap opposite the opening, by utilizing a venturi effect created by part of the inlet gas flow which is split off into a peripheral gas flow to flow around the acoustic trap through a constricted area just ahead of the vent holes, created by the acoustic trap and the adjacent casing wall or adjacent trap, so as to create a low pressure zone at the vent holes to continuously draw gas out of the acoustic trap. The acoustic traps may be oriented in a single or multiple linearly extending staggered groups, with in-line or offset inlets and outlets.
In this regard, my previously issued U.S. Pat. No. 5,824,972 issued to me Oct. 20, 1998 titled xe2x80x9cAcoustic Mufflerxe2x80x9d, and my U.S. patent application Ser. No. 09/393,398 titled xe2x80x9cThin Boom Tube Exhaust Pipes, Method of Sheet Metal Construction Thereof, and Exhaust Systems Which Utilize Such Exhaust Pipes For Increased Ground Clearance On Race Cars,xe2x80x9d now U.S. Pat. No. 6,283,162, are hereby incorporated by reference into this patent application.
The invention comprises a flattened profile acoustic muffler exhaust pipe, or acoustic muffler boom tube exhaust pipe for attachment to the end of a secondary exhaust pipe or exhaust pipe header assembly leading exhaust gasses away from the engine of a motor vehicle. The boom tube exhaust pipe mounts to the bottom portion of the frame or chassis of the motor vehicle typically adjacent the side of the vehicle and provides improved ground clearance between the exhaust pipe and the surface of the ground. The exhaust pipe includes one or more spiral acoustic traps utilizing a circular mixing process with increased gas retention time to attenuate acoustic noise more effectively than an absorption muffler and with substantially less back pressure than friction mufflers.
The boom tube exhaust pipe is of generally tubular configuration, comprising a tubular inlet having a first end of mating configuration for attachment to a secondary exhaust pipe or to an exhaust pipe header assembly, having an inlet opening for receiving exhaust gasses therefrom of generally circular or slightly flattened circular shape with the secondary exhaust pipe or exhaust pipe header assembly having a mating shape, the tubular inlet tapering from the first end to a second, thin profile, generally flattened end, a tubular body of generally flattened shape corresponding to the second end of the tubular inlet, which tubular body extends therefrom and which terminates at an outlet opening for expelling the exhaust gasses into the atmosphere, and one or more spiral acoustic traps strategically placed inside the tubular body. The spiral shaped acoustic traps provide circular mixing of a main gas flow combined with a venturi effect created around the traps by a peripheral gas flow which draws the gas from the acoustic traps through outlet vents in the acoustic traps provides effective acoustic muffling while achieving high flow rates with minimal back pressure.
Each spiral acoustic trap comprises a single, preferably thin wall, which is loosely wrapped about a central axis and which wall spans between opposing casing top and bottom walls. The spaced ends of the acoustic trap define an entrance opening through which gas can enter into an inner chamber formed by the acoustic trap wall, and opposing top and bottom casing walls. A series of vent holes extend through the acoustic trap wall in an appropriate location away from the opening to allow gas flow from the inner chamber.
When inlet gas flows through the casing inlet it is split into one or more main gas flows and one or more smaller peripheral gas flows, each of which flow in the general direction of an outlet in the casing. The main gas flow moves on the open side of each acoustic trap, i.e., the side with entrance opening, with the central axis of each trap extending substantially perpendicular to the main gas flow, and the entrance opening of each trap located in the main gas flow so as to divert a portion of the main gas flow into the inner chamber. The diverted gas forms an inner chamber gas flow which travels in a continuous circular mixing motion so as to break up the sound waves into random molecular motion, adding heat energy to the gas.
The peripheral gas flow travels on the opposite side, or back side of the spiral acoustic traps from the entrance opening. The volume and rate of peripheral gas flow may be set by a perforated metering screen, a metering plate, or other appropriate restriction, which partially or completely covers the opening between the backside of the first trap of each group, the side wall, and opposing casing top and bottom walls. The back side of each trap, along with the casing side wall or other acoustic traps, form a venturi through which the peripheral gas flow is accelerated to form a low pressure zone. A series of vents or outlets through each acoustic trap wall may be present between the inner chamber gas flow and the low pressure zone to draw gas from the inner chamber, in the form of a vent gas flow, into the peripheral gas flow to make room for more of the main gas flow to enter the inner chamber to join the inner chamber gas flow. While providing a vent or outlet through the trap wall enhances air flow through the trap to better absorb more of the acoustic energy such vents or outlets may not be absolutely required. Also, one or more vents or outlets may be present in the casing leading from the traps to the outside of the casing. In this configuration, a low pressure area or venturi effect may be present to assist in pulling gases from the traps.
The acoustic traps are generally placed in one linearly diagonally extending group of acoustic traps so as to maximize the uptake of the main gas flow yet minimize the increase in exhaust gas backpressure, with the spiral acoustic traps offset such as by about half a trap width, and with each successive trap overlapping the main gas flow further. Other configurations are possible including multiple linearly diagonally extending groups and the other configurations in my U.S. Pat. No. 5,824,972.
The tubular inlet is typically configured such that the bend radius of respective side portions of the tubular inlet typically decreases uniformly from the first to second end thereof unlike prior art inlets. The flattened tubular body can include a bottom surface lying generally in a plane with the bottom of the tubular inlet at or above the lower plane in a mounted position on the motor vehicle allowing all of the other pipes of the exhaust system lie at or above such plane so as to maximize ground clearance. The body can be flared laterally outwardly from the tubular inlet to the outlet opening so as to allow the exhaust gasses to expand while moving through the body yet without decreasing the ground clearance of the boom tube exhaust pipe.
A structural rib can extend generally longitudinally through the tubular inlet, which structural rib is tapered so as to span between and is affixed to the tubular inlet juxtaposed an upper and a lower inside surface of the tubular inlet, so as to provide support to the tubular inlet. Such structural rib can include a generally non-tapered portion which extends into the tubular body, which structural rib spans between and is also affixed to the tubular body juxtaposed an upper and a lower inside surface of the tubular body. One or more structural ribs can extend generally longitudinally through the tubular body, which structural ribs are typically split and longitudinally spaced so as to provide room for the diagonally disposed spiral acoustic traps, which structural ribs span between and are affixed to the tubular body juxtaposed an upper and a lower inside surface of the tubular body, so as to provide support to the tubular body. A plurality of holes can extend through the structural rib to allow exhaust gasses to flow between elongate passageways formed on each side of the structural ribs, the tubular inlet, and the body. The structural rib can comprise a web interconnecting respective upper and lower legs or flanges which extend laterally therefrom, such as in a C-shaped channel cross-section, which structural rib can be plug welded to the tubular inlet and the body through a plurality of holes such as round holes or slots through the tubular inlet and body.
The exhaust pipe can include a pair of tubular inlets of similar construction to the first and laterally adjacent for attachment to first and second secondary exhaust pipes. A structural rib can extend generally longitudinally through each tubular inlet, which structural ribs are tapered so as to span between and is affixed to the respective tubular inlet juxtaposed an upper and a lower inside surface of the respective tubular inlet, so as to provide support to the respective tubular inlet. Such structural ribs can each include a generally non-tapered portion which extends into the tubular body, which structural ribs span between and is also affixed to the tubular body juxtaposed an upper and a lower inside surface of the tubular body. One or more structural ribs can extend generally longitudinally through the tubular body, which structural ribs are typically split and longitudinally spaced so as to provide room for the diagonally disposed spiral acoustic traps, which structural ribs span between and are affixed to the tubular body juxtaposed an upper and a lower inside surface of the tubular body, so as to provide support to the tubular body. Such structural ribs typically include a center structural rib which extends generally longitudinally through the body generally laterally centered therein between the respective inlets and structural ribs thereof and a pair of structural ribs generally longitudinally aligned with such inlets and spaced from the structural ribs thereof. The structural ribs provide further support to the body, reducing vibration and resulting fatigue failure of the metal of the body. On the dual inlet versions, laterally adjacent portions of the inlets can be vertically cut so as to mate or merge together laterally and be welded at the periphery therebetween to place the inlets closer together.
The invention further comprises acoustic muffler exhaust pipes constructed from standard sheet metal which can be sheared, punched, and formed on standard hand operated punch presses and breaks or other comparable press to allow low cost, low volume production thereof as well as on high volume Computer Numerically Controlled (CNC) programmable punch presses and multiple station automated progressive stamping machines. The tubular inlet and body comprise a pair of sheet metal half shells which are welded together such as at respective peripheral seams. The half shells can comprise respective upper and lower half shells each of which can comprise inlet and body halves which are generally laterally welded together. The structural rib comprises a piece of sheet metal formed so as to have a longitudinally-extending web which interconnects respective laterally outwardly bent upper and lower legs or flanges which extend generally normally therefrom, such as forming a C-shaped channel cross-section. The portion of the structural rib which extends into the inlet is tapered so as to span between an upper and a lower inside surface of the inlet, such tapered portion being formed such as by splitting the upper and/or the lower leg or flange and forming at an angle relative to the remainder thereof. A plurality of punched holes can extend through the web of the structural rib to allow exhaust gasses to flow therethrough. The spacer ribs are constructed in a similar manner from sheet metal but without the tapered inlet portion. The structural ribs and spacer ribs can be plug welded to the half shells through a plurality of holes such as round holes or slots through the respective half shells. Single or dual inlet boom tube exhaust pipes can be made using such construction. On the dual inlet versions, laterally adjacent portions of the inlet halves of the upper and lower half shells can be vertically cut so as to mate or merge together laterally and be welded at the periphery between the inlet halves to place the inlets closer together.
The invention further comprises exhaust systems which include the acoustic muffler exhaust pipes of the invention, such exhaust systems being for use on motor vehicles powered by an internal combustion engine having multiple power cylinders. Such exhaust systems comprise a pair of exhaust pipe header assemblies each of which include a plurality of primary exhaust pipes each connectable at a first end thereof to the engine block at a respective power cylinder exhaust port and a merge collector into which respective opposite ends of the primary exhaust pipes converge and are welded, a pair of transition pipes each having a first end connectable to one of the merge collectors and each having a second end, and a single boom tube exhaust pipe having a pair of inlets, or a pair of acoustic muffler exhaust pipes each having a single inlet. The second ends of the transition pipes are connectable to the respective inlets of the single or dual inlet boom tube exhaust pipes. The single inlet version diverges to laterally opposite sides of the motor vehicle and the dual inlet version exits to one side of the motor vehicle.
The invention further comprises a method of construction of an acoustic muffler exhaust pipe from standard sheet metal, comprising the steps of providing a pair of upper and lower half shells of formed sheet metal which include an inlet portion, a body portion, and an outer periphery, providing a spiral acoustic trap formed of sheet metal, providing an elongate rib of formed sheet metal having a web which interconnects a pair of respective upper lower legs or flanges which extend laterally outwardly therefrom, placing the spiral acoustic trap and the rib generally longitudinally within the half shells, welding the spiral acoustic trap and the rib to the respective upper and lower half shells, and welding the outer peripheries of the half shells together. The method can be practiced wherein the welding of the spiral acoustic trap and the rib to the respective upper and lower half shells is of the resistance spot welding type, or by using half shells each of which include a plurality of longitudinally extending plug weld holes such as round holes or slots punched therethrough and plug welding the spiral acoustic trap and the rib to the respective upper and lower half shells through the plug weld holes. The half shells can comprise upper and lower half shells. Each of the upper and lower half shells can comprise separate inlet and body halves and the method further include welding the inlet and body halves of the respective upper and lower half shells together. The method can include construction of dual inlet boom tube exhaust pipes having a pair of structural ribs. The inlet halves of the upper and lower half shells can be made from separate pieces of sheet metal and can be vertically cut so as to mate or merge together laterally and the inner periphery between the inlets halves of the upper and lower half shells welded together. The method can include construction of a boom tube exhaust pipe having a center structural rib and/or a pair of structural ribs each disposed laterally outside one of the respective structural ribs in the inlets.
The single and dual inlet acoustic muffler exhaust pipes of the invention, exhaust systems which include such exhaust pipes, and the methods of construction thereof can include acoustic muffler exhaust pipes which are also acoustic mufflers, all of which this invention further comprises.
As such the tubular inlet or inlets and in particular the flattened tubular body of the boom tube exhaust pipe comprise the casing of the muffler and a plurality of spiral acoustic traps disposed therein provide the acoustic attenuation. The specific configurations of the combined boom tube exhaust pipe acoustic muffler include any of those disclosed in my prior xe2x80x9cAcoustic Mufflerxe2x80x9d patent, with a single longitudinally diagonally disposed row of acoustic traps being preferred in both the single and the dual inlet versions of the boom tube exhaust pipe acoustic muffler. In such configuration as well as in the other configurations thereof, any such structural ribs and/or spacer ribs can include longitudinal gaps between which the spiral acoustic traps can extend. Such boom tube exhaust pipe acoustic mufflers can also include metering screens, deflectors such as a V-shaped inlet deflector, and perforated metering plates, or any other such components disclosed in my prior xe2x80x9cAcoustic Mufflerxe2x80x9d patent. Such spiral acoustic traps can be affixed to the casing such as by fillet welding, plug welding, or resistance spot welding. The spiral acoustic traps can include one or more upper and lower locator tabs which are integral with or affixed to the spiral acoustic traps and which extend vertically upwardly and downwardly through corresponding generally rectangular or arcuate rectangular holes through the upper and lower walls of the casing or half shells. Such holes serve to locate and retain the spiral acoustic traps during assembly. Such tabs can be bent over upon assembly and are affixed to the casing such as by welding. Alternatively, such tabs can comprise bent ninety degree bent tabs integral with or separate pieces affixed to the spiral acoustic traps, which bent tabs fit juxtaposed the upper and lower surfaces of the casing, which tabs can be welded in a similar manner to the structural ribs, spacer ribs, and spiral acoustic traps. Such locating tabs and corresponding holes in the casing or half shells, and bent tabs can likewise be used on the metering screens, deflectors, perforated metering plates, and on any other such components used in the construction of the boom tube exhaust pipe acoustic muffler.
The boom tube exhaust pipe acoustic muffler can include other means for acoustic attenuation, such as a plurality of flat, curved, V-shaped, or otherwise bent baffle plates which route the exhaust gasses in a circuitous route therethrough so as to provide acoustic attenuation so as to lower the level of noise from the motor vehicle. Examples of such baffle arrangements in single and dual inlet versions include laterally extending, longitudinally spaced flat baffle plates which alternately extend from opposite sides of the casing with respective gaps between the free ends thereof and the opposite side portion of the casing for exhaust gasses to pass thereby so as to route the exhaust gases side-to-side in a generally horizontal plane. Such baffle plates can comprise laterally extending ribs of similar construction to the structural ribs and spacer ribs disclosed herein. The ends of the respective ribs which contact the side portions of the casing can be arcuate so as to match closely thereto without significant exhaust gas leakage therebetween. A second example of such baffle arrangement comprises a longitudinally extending series of alternating generally laterally disposed-V-shaped plates and pairs of flat plates, the V-shaped plates disposed generally along the longitudinal centerline of the casing pointing toward the tubular inlet with gaps between the respective ends thereof and the side portions of the casing to allow exhaust gasses to pass thereby. The flat plates extend from respective side portions of the casing in a generally coplanar fashion, with a gap between the free ends thereof at the longitudinal centerline of the casing to allow exhaust gasses to pass thereby. As such, the exhaust gasses are generally split into two streams which pass by opposite ends of each V-shaped baffle plate and remix in the gap between the flat plates.
Other such examples of such arrangements of baffle plates include such as for the dual inlet version a pair of such above examples, comprising two complete sets of baffle plates as described in the previous examples, one generally centered about the longitudinal centerline of each of the respective inlets, the innermost plates of which can terminate at the center spacer rib rather than the side portion of casing or simply terminate such that exhaust gasses can pass therearound.